The hotly-contested DFL Senate primary is now the most expensive in Minnesota history. DFL candidates Mike Ciresi and Mark Dayton have put more than $8.7 million of their own money into the race, while Democrat Rebecca Yanisch has put more than a half a million dollars into her campaign. But campaigns also rely to varying degrees on individual contributors, people who are willing to write a check for $50 or a $100 or $1,000, the maximum allowed by law, to candidates they support. Minnesota Public Radio's Laura McCallum looks at the individual contributors in the Senate race.